There has been a known conventional technique that displays names of a plurality of menus as a menu list on a display device. Each menu belongs to a corresponding layer configuring a hierarchical structure. In the menu list, the names of the plurality of menus are arranged along a line intersecting a line parallel to a width direction of a displaying means. In relation to this technique, Japanese Patent Application Publication JP2002-514328 (page 18, paragraph 3, FIG. 5)) describes a technique that, when each menu list is displayed from the left to the right of a screen sequentially from a highest layer, the screen displays a menu list of a layer requested to be displayed and a menu list of a layer immediately higher than such layer. Menu lists of a layer even higher than these layers is hidden by scrolling the screen from the right to the left.